The general objective of this research is to evaluate the relative effectiveness of different approaches to implementing a promising school-based smoking prevention program. The program will be tested in a longitudinal field study of a defined population of children utilizing an experimental research design. The intervention program is the Smoking Prevention Component (SPC) of the Know Your Body School Health Education Program (KYB). The Know Your Body Program is a multicomponent, school health education program which emphasizes positive lifestyle change through decision making skills and self-responsibility. The focus of KYB is the prevention of cancer and cardiovascular disease. In addition to impact, process and outcome evaluations of the KYB/SPC intervention, a comprehensive cost-efficiency evaluation of different intervention approaches will be carried out. Specifically, two different approaches will be compared in terms of program efectiveness and cost-efficiency: a) The Smoking Prevention Component embedded within the multicomponent KYB Program (the KYB/SPC approach) b) the SPC as a stand-alone intervention, without the other components of KYB (the SPC approach) In addition, a highly controlled substudy has been incorporated into the basis research design. This substudy will involve the development and pilot testing of an enhanced parental involvement program to be evaluated in conjunction with the KYB/SPC program and with the SPC alone.